{/*   FOUR FUNCTION CALCULATOR: FFCALC.SYN           */}

// -- CONFIGURATION SECTION ----------------------------
[
  default token type = double
  disregard white space
  lexeme { real}
  event driven
  reentrant parser
  mutex type = HANDLE
]

// -- FOUR FUNCTION CALCULATOR -------------------------
(void) calculator $
 -> [calculation?, '\n']..., eof

(void) calculation
 -> expression:x                      =printf("%g\n",x);
 -> name:n, '=', expression:x                         ={
                  printf("%c = %g\n",n+'A',value[n]=x);}
 -> error

expression
 -> term
 -> expression:x, '+', term:t                     = x+t;
 -> expression:x, '-', term:t                     = x-t;

term
 -> factor
 -> term:t, '*', factor:f                         = t*f;
 -> term:t, '/', factor:f                         = t/f;

factor
 -> name:n                                   = value[n];
 -> real
 -> '(', expression:x, ')'                          = x;
 -> '-', factor:f                                  = -f;

// -- LEXICAL UNITS ------------------------------------
digit   = '0-9'
eof     = 0

(void) white space
 -> ' ' + '\t' + '\r' + '\f' + '\v'
 -> "/*", ~eof?..., "*/"

(int) name
 -> 'a-z' + 'A-Z':c                             = c-'A';

real
 -> integer part:i, '.', fraction part:f          = i+f;
 -> integer part, '.'?
 -> '.', fraction part:f                            = f;

integer part
 -> digit:d                                     = d-'0';
 -> integer part:x, digit:d              = 10*x + d-'0';

fraction part
 -> digit:d                                =(d-'0')/10.;
 -> digit:d, fraction part:f           =(d-'0' + f)/10.;

{ /* -- EMBEDDED C ---------------------------------- */
  #include <stdio.h>

  double value[64];                      /* registers */
  int main(int argc, char *argv[]) {
    FILE *input;
    long length;
    char *buf;
    ffcalce_pcb_type pcb;
    int i;
    if (argc < 2) {
      printf("Usage: ffcalcp <file name>\n");
      return 1;
    }
    input = fopen(argv[1], "r");
    if (input == 0) {
      printf("Cannot open %s\n", argv[1]);
      return 2;
    }
    fseek(input, 0, SEEK_END);
    length = ftell(input);
    fseek(input, 0, SEEK_SET);
    buf = malloc(length);
    length = fread(buf, 1, length, input);
    buf[length++] = 0;
    init_ffcalce(&pcb);
    for (i = 0; i < length && pcb.exit_flag == AG_RUNNING_CODE; i++) {
      pcb.input_code = (unsigned) buf[i];
      ffcalce(&pcb);
    }
    return 0;
  }
} /* -- END OF EMBEDDED C ----------------------------*/